The present invention concerns a label dispenser to issue and apply stick-on labels and which in every operational cycle moves a stick-on label into a dispensing position below a compression roller provided with a contoured surface and a sleeve by means of which the compression roller is rotatably supported on a fixed shaft.
Such a label dispenser is known from German Patent No. 30 30 153. This known label dispenser has a compression roller with a contoured surface and sleeve by means of which this compression roller is rotatably supported on a fixed shaft. The roller is a relatively soft plastic in order to achieve some matching of this compression roller to the surface of the object to be labeled.
Immediately before being deposited, the label is printed. The printing ink does not dry by evaporation, but rather by penetrating the label material. It does happen, on account of the rapid operational sequence during marking and labeling, that the contoured surface comes into contact with printed symbols which have not yet dried. The soft plastic tends to adsorb but not absorb the ink. This means that the ink-wetted portion of the surface at its next contact with a label or with the surface of the object to be labeled will deposit the ink thereon. As a result, unsightly streaks appear on the printed labels. These streaks are particularly disadvantageous where the labels must be provided with machine-readable print. Frequently, these streaks make automatic reading by photo-electric converters impossible.
It is furthermore known (German Offenlegungsschrift No. (32 07 053) to use a relatively hard plastic for the rollers. This material is highly ink-repellant, whereby the above streaking is largely averted. In order to obtain the required elasticity in the compression roller (i.e., matching to the surface of the object to be labeled), the compression roller of the known dispenser is rotatably supported at a middle zone of its length on an elastically deformable shaft. This middle zone is adjoined on both sides by shaft passages extending as far as the end faces of the compression roller, the compression roller surrounding the shaft with play within these passages.
While compression rollers of this kind substantially avoid unintended soiling of the labels by ink streaks, a matching of the surface to the objects being labeled on the other hand is possible in only a limited way. Essentially, such matching is limited to oblique surfaces. Such compression rollers make it difficult and perhaps impossible to presss the labels in a fully adhering manner illustratively on transversely curving surfaces such as bottles and cans.
Based on the state of the art of the label dispenser of the German Patent No. 30 30 153, it is the object of the present invention to create a compression roller with the required elasticity to match the surface of the object to be marked without thereby adversely affecting the print quality of the label.
This problem is solved by the invention by the compression roller being provided with individual, cross-sectionally contoured rings supported on a sleeve by spring elements mounted to their interiors.
This design makes it possible to fit the compression roller to the particular requirements, i.e. matching to the label format an arbitrary number of cross-sectionally contoured rings.
Furthermore, it is possible to use a hard roller material for these rings and thereby to avoid the danger of ink adsorption. In spite of the hard material of the rings, the compression roller is highly elastic, because of the inset spring elements, whereby it can match in an outstanding manner the particular topologies of the labeled objects.
Preferably, the spring means are mounted in mutually opposite grooves inside the cross-sectionally contoured rings, i.e., on the outside of the sleeve. Typically, such spring means are composed of a rubber material.
Preferably, the sleeve is of one piece.
In an especially preferred embodiment, the sleeve comprises individual sleeve elements, the ring length being less than the sleeve-element length. This embodiment makes it possible to change the length of the compression roller by serially arranging several sleeve elements with corresponding shaped rings and thereby to achieve a more extensive match for the particular label dispensers used.
In another especially preferred embodiment, the sleeve comprises individual sleeve elements, with the length of the cross-sectionally contoured rings being equal to the sleeve-element length. Spacer rings are preferably used in this embodiment with an outside diameter less than that of the contoured rings. Advantageously, the length of two such spacer rings equals the length of one contoured ring. This embodiment is especially advantageous because tipping or warping of the shaped rings is prevented thereby.
In a further especially preferred embodiment, the cross-sectionally contoured rings have different outside diameters. This embodiment makes it possible in an especially simple way to apply labels to transversely curved surfaces such as conical insides in the textile industry and the outsides of bottles and cans.